Pneumatic tool



W. A. SMITH PNEUMATIC TOOL June 11, 1929.

Filed Sept. 2, 1927 INVENTOR. William Axf'mi [A BY%' 15 ATTNEY. V

Patented June 11, 1929.

' TAT ears.

WILLIAM A. SIiIITH', OF SAYBE, PENNSYLVANIA, ASSIGNOB 'IO INGERSOLL-BAND COMPANY, OF JERSEY CITY, NEW JERSEY, A COREORATIDN OF NEW JERSEY.

PNEUMATIC TOOL.

Application filed September This invention relates to pneumatic tools, but more particulz-nrly to a relief valve for fluid actuated tools of the hammer type.

The objects of the invention are to relieve the compression from the ends of the cylinder and to'effect such relief from one end of the cylinder in synchronism with the admission of pressure fluid to the opposite end of the cylinder.

Other objects will appear hereinafter.

In the drawings illustrating a practical application of the invention,

Figure 1 is an elevation in section of a pneumatic tool constructed in accordance with the practice of the invention and showing the distributing and relief valves in the respective positions which they will assume during the admission of pressure fluid tothe rearward end of the cylinder, and

Figure 2 is a view similar to Figure 1 showing the valves in their other extreme positions.

Referring more particularly to the drawings, A designates a cylinder of a pneumatic tool having a free exhaust port B which in this instance is controlled by a hammer piston G reciprocable in the cylinder A. The cylinder A may be of a well known type in which a working implement 1) extends directly into the front end thereof to receive the blows of the hammer piston C.

Disposed on the end of the cylinder A for which it forms a closure is a valve block E having a bore opening in this instance from the rearward end of the block E to form a relief valve chamber F. The rearward end of the valve chamber F is closed by a plate G which seats on the rearward end of the block E and maybe of substantially the same exterior conformation as the block E. In addition to the function described, the plate G also acts as a seat for a distributing valve H of the plate type adapted to oscillate in a distributing valve chamber J formed in this instance bya plate K, said plate being of a suitable thickness to determine the height of the valve chamber J and consequently the lift of the valve H. The valve H may be of a well known type and in this instance is pivoted on a pin L seated in a plate O which forms a cover for the valve chamber J and also acts as a seat for a back head P.

Any suitable means may be employed for securing together those parts comprising the the front end of the valve chamber F.

2, 1927. Serial No. 217,119.

casing of the drill such as the cylinder A, the back head P, the block E and the plates G, O and J. Preferably, such means consists of the usual side rods (not shown).

Pressure fluid for actuating the piston C may be admitted to the drill from a suitable source of supply (not shown) through a passage Q in the back head P. The passage Q may flare outwardly at its inner end to communicate with supply ports R and S opening into the valve chamber J preferably at the outer edge of the valve chamber J and directly over the edges of the valve H. Leading from the valve chamber J to the rearward end of the cylinder A is an inlet passage S to convey pressure fluid to the rearward end of the cyl nder. A similar 1nlet passage T leads from the opposite end I of the valve chamber J to the front end of the cylinder.

According-to the present invention, means are provided for relieving the compression formed in the ends of the cylinder by the piston C. This means in the present instance consists of a relief valve designated generally by U and comprises a pair of end heads V and N which cooperate slidably with thewall of the valve chamber F and are connected by a reduced stem X. In order to actuate the relief valve U in a rearwardly direction by the pressu'reiiuid, a kicker passageY is formed in the valve block E to connect the inlet passage T with A similar kicker passage Z is in this instance formed in the plate G to connect the rearward end of the valve chamber F with the inlet passage S" for conveying pressure fluid into the rearward end of the valve chamber F to actuate the valve U in a forwardly direction. The kicker passages Y and Z in this instance also serve to convey the pressure fluid used for actuating the valve U from the ends of the valve chamber F to the inlet passages.

In the present instance, the inlet passages T and S are utilized for conveying the compression from the ends of the cylinder, that from the front end of the cylinder passing through the inlet passage T, thence through a port Z) into an annular groove 0 in the valve chamber F, said groove 0 being controlled by the head Wof the valve U. To provide an escape for the compression in the rearward end of the cylinder through the inlet passage S, a port (Z leading from the said inlet passage S communicates with an annular groove 6 in the rearward end of the I block E, said exhaust passage leading from a point in the valve chamber intermediate the ends of the valve chamber F and between the annular grooves e and c to the atmosphere.

The operation of the device is as follows: lVith the valves H and U in the positions illustrated in Figure 1, pressure fluid will flow through the ports over the raised end of the valve H, thence through the inlet passage S into the rearward end of the cylinder A to actuate the piston C forwardly. During the admission of pressure fluid to the rearward end of the cylinder, a portion thereof will also pass through the kicker passage Z into the rearward end of the valve chamber F to act against the corresponding end of the valve U for holding said valve in the forward end of the valve chamber F, thus cutting off communication between the inlet passage S and the exhaust port f.

In the extreme forwardmost position of the valve U the annular groove 0 will be uncovered by the head WV, to establish communication between the front end of the cylinder A and the atmosphere for the escape of compression through the inlet passage T, the port d, the annular groove 0 and the exhaust port f.

' the raised end of the valve H. As a result of this decreased pressure, the air flowing over the edge of the valve will, due to the suction created thereby, tilt the valve H to close the inlet passage S and at the same time open the inlet passage T thus permitting pressure fluid to flow into the front end of the cylinder for reversing the travel of the piston 0.

During the admission of pressure fluid to the front end of the cylinder A, a portion of the pressure fluid will pass through the kicker passage Y and, acting against the front end of the relief valve U, will throw said relief valve to its rearward extreme position. In this position of the relief valve U, the head of said valve will cut off communication between the inlet passage T and the exhaust port 7 and the annular groove 6 will be uncovered by the head V. In this way is established a direct path for the escape of compression from the rearward end of the cylinder A through the inlet passage S, the port d, thence through the annular groove 0 and the exhaust port f to the atmosphere.

I claim: V

In a pneumatic tool, the combination of a cylinder and piston, a valve chest having a distributing chamber and a relief chamber, inlet passages leading from the distributing chamber to the ends of the cylinder, a distributing valve in the distributing chamber controlling the inlet passages, an exhaust port leading from a point intermediate the ends of the relief chamber to the atmosphere, a relief valve in the relief chamber, kicker passages in the valve chest conveying pressure fluid from the inlet passages .to the ends of the relief'chamber for actuating the relief valve, said kicker passages also serving to convey such pressure fluid from the ends of the relief chamber to the inlet passages, and ports leading from the inlet passages to the relief chamber for conveying compression from the ends of the cylinder.

.In testimony whereof I have signed this specification.

' WVILLIAM A. SMITH. 

